1. GEAR
• Power transmission is the movement of energy
from its place of generation to a location where
it is applied to performing useful work
• A gear is a component within a transmission
device that transmits rotational force to another
gear or device
2. GEAR
Power & Torque
• POWER is Measurement of how quickly work
can be done
• Turning effect of force is called TORQUE
• Power is dependent upon Torque & RPM
• HORSEPOWER= Torque x RPM
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3. TYPES OF GEARS
1. According to the position of axes of the
shafts.
a. Parallel
1.Spur Gear
2.Helical Gear
3.Rack and Pinion
b. Intersecting
Bevel Gear
c. Non-intersecting and Non-parallel
worm and worm gears
4. SPUR GEAR
Teeth is parallel to axis
of rotation
Transmit power from
one shaft to another
parallel shaft
Used in Electric
screwdriver, oscillating
sprinkler, windup alarm
clock, washing machine
and clothes dryer
6. Helical Gear
The teeth on helical gears are cut at an angle
(15 to 45) to the face of the gear
This gradual engagement makes helical gears
operate much more smoothly and quietly than
spur gears
One interesting thing about helical gears is
that if the angles of the gear teeth are correct,
they can be mounted on perpendicular shafts,
adjusting the rotation angle by 90 degrees
8. Herringbone gears
To avoid axial thrust, two
helical gears of opposite
hand can be mounted side
by side, to cancel resulting
thrust forces
Herringbone gears are
mostly used on heavy
machinery.
9. Rack and pinion
Rack and pinion gears
are used to convert
rotation (From the
pinion) into linear
motion (of the rack)
A perfect example of
this is the steering
system on many cars
10.
11. Bevel gears
Bevel gears are useful when the direction of a shaft's
rotation needs to be changed
They are usually mounted on shafts that are 90
degrees apart, but can be designed to work at other
angles as well
The teeth on bevel gears can be straight, spiral or
hypoid
locomotives, marine applications, automobiles,
printing presses, cooling towers, power plants, steel
plants, railway track inspection machines, etc.
13. WORM AND WORM GEAR
Worm gears are used when large gear reductions are
needed. It is common for worm gears to have
reductions of 20:1, and even up to 300:1 or greater
Many worm gears have an interesting property that
no other gear set has: the worm can easily turn the
gear, but the gear cannot turn the worm
Worm gears are used widely in material handling
and transportation machinery, machine tools,
automobiles etc
15. GEAR TRAINS
A gear train is two or more gear working
together by meshing their teeth and turning
each other in a system to generate power and
speed
It reduces speed and increases torque
Electric motors are used with the gear systems
to reduce the speed and increase the torque
16. Types of Gear Trains
Simple gear train
Compound gear train
Planetary gear train
Simple Gear Train
The most common of the gear train is the gear pair
connecting parallel shafts. The teeth of this type can
be spur, helical or herringbone.
Only one gear may rotate about a single axis
20. Planetary Gear Train…
• In this train, the blue gear has six times the diameter
of the yellow gear
• The size of the red gear is not important because it is
just there to reverse the direction of rotation
• In this gear system, the yellow gear (the sun) engages
all three red gears (the planets) simultaneously
• All three are attached to a plate (the planet carrier),
and they engage the inside of the blue gear (the ring)
instead of the outside.
21. Gear Raitos
• When two gears are mesh, a gear raito exists
• Driven Gear = Raito
Driver Grear
• Example
• Driver gear has 14 teeth & Driven gear has 28 teeth
• 28/14= 2:1
• The driver gear must rotate twice to make the driven
gear rotate once
22. Derivation
• R.P.M 1/dia
• Dia teeth
• So,
• R.P.M 1/teeth
• As we know that RPM is speed so
• Speed 1/teeth
• Speed=K/teeth
• Speed x Teeth = k (where speed n teeth can be driver
n driven)
• = Speed(driver) x Teeth(driver)
Speed(driven) x Teeth(driven)
